<!DOCTYPE html>
<html>

<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }
        
        .wrap {
            width: 300px;
            margin: 100px auto 0;
        }
        
        table {
            border-collapse: collapse;
            border-spacing: 0;
            border: 1px solid #c0c0c0;
            width: 300px;
        }
        
        th,
        td {
            border: 1px solid #d0d0d0;
            color: #404060;
            padding: 10px;
        }
        
        th {
            background-color: #09c;
            font: bold 16px "微软雅黑";
            color: #fff;
        }
        
        td {
            font: 14px "微软雅黑";
        }
        
        tbody tr {
            background-color: #f0f0f0;
        }
        
        tbody tr:hover {
            cursor: pointer;
            background-color: #fafafa;
        }
    </style>

</head>

<body>
    <div class="wrap">
        <table>
            <thead>
                <tr>
                    <th>
                        <input type="checkbox" id="j_cbAll" />
                    </th>
                    <th>商品</th>
                    <th>价钱</th>
                </tr>
            </thead>
            <tbody id="j_tb">
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>iPhone8</td>
                    <td>8000</td>
                </tr>
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>iPad Pro</td>
                    <td>5000</td>
                </tr>
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>iPad Air</td>
                    <td>2000</td>
                </tr>
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>Apple Watch</td>
                    <td>2000</td>
                </tr>

            </tbody>
        </table>
    </div>
    <s></s>
</body>

<script>
    let nodeTbody = document.querySelector('#j_tb');
    //console.log(nodeTbody);
    let inputs = nodeTbody.querySelectorAll('input');
    //console.log(inputs);
    let inputall = document.querySelector('#j_cbAll');
    //console.log(inputall);
    //console.log(inputall.checked);
    inputall.onclick = function() {
        if (this.checked) {
            for (let i = 0; i < inputs.length; i++) {
                inputs[i].checked = true;
            }
        } else {
            for (let i = 0; i < inputs.length; i++) {
                inputs[i].checked = false;
            }
        }
        //console.log(inputs);
    }
    for (let i = 0; i < inputs.length; i++) {
        inputs[i].onclick = function() {
            for (let i = 0; i < inputs.length; i++) {
                if (!inputs[i].checked) {
                    inputall.checked = false;
                    return;
                }
            }
            inputall.checked = true;
        }
    }
</script>

</html>